1. Field of the Invention
This invention relates to well tools and more particularly relates to guides for sucker rods used to drive a sub-surface well pump in the production tubing of a well for lifting well fluids through the tubing to the surface.
2. History of the Prior Art
Well fluids, particularly oil, in situations where there is no natural formation drive, are often produced by reciprocating pumps positioned in the well at a depth at which the oil and related fluids flow into the well bore. The pump is driven by a sucker rod connected between a pumping jack at the surface end of the well and the pump plunger. The sucker rod is a string of end-to-end connected rod sections extending downwardly in the well production tubing. More often than not the production tubing of a well is not straight but rather deviates in a number of different configurations sufficiently to cause the sucker rod to rub against the tubing wall surface. Such rubbing produces wear along some of the sucker rod sections and the production tubing wall. It has been standard practice for many years to minimize sucker rod and production tubing wall wear as well as to improve the efficiency of operation of a sucker rod by holding the sucker rod centrally disposed in the production tubing with rod guides. The rod guides are fabricated of materials which minimize friction and are configured to permit well fluids to flow past the guides within the production tubing. Such guides are normally slotted to permit installation of the guides on the rod by pressing them laterally from the side of the rod rather than requiring insertion of the rod at one end through the guides. Once the guides are pressed on the sucker rod they preferably grip the rod sufficently tightly to prevent slippage of the rod in the guide as the rod and guides reciprocate. Typical prior art sucker rod guides formed of soft materials such as oil resistent rubber and requiring metal inserts for holding the guides on the sucker rods are shown in the following U.S. Pat. Nos.: 2,655,113; 2,793,917; 2,928,472; 3,001,834; 3,186,773; and 3,650,579. In some of the guides shown in these prior art patents, the insert fits within the bore of the guide and grips the surface of the sucker rod. In other prior art patented rod guides the insert is embedded within the guide material squeezing the guide against the sucker rod surface. Such rod guide designs are shown in U.S. Pat. Nos. 3,001,834 and 3,414,337. The use of such guides requires both additional manufacturing and assembly costs and precedures. A still further prior art sucker rod guide is shown in U.S. Pat. No. 3,442,558 which has upper and lower sections provided with misaligned longitudinal bores each of which communicates with longitudinal, radially extending slots which increases in width from the narrowest portion at the outer surface of the guide to the widest portion where the slot opens into the guide bore.